In vehicle safety technology, data regarding the current driving situation of the vehicle is collected using sensors. This data is made available to the vehicle safety devices, e.g. airbag systems or vehicle dynamics control, such as ESP or ESC which can control the vehicle or parts thereof using this data.
The measuring section of these sensors is e.g. a microsystem such as a micro-electro-mechanical system (MEMS element) or a micro-opto-electro-mechanical system (MOEMS element).
If one of these sensors malfunctions or supplies false measuring values owing to a defect, the measuring values of this malfunctioning sensor must be replaced with other measuring values or at least be approximated so that the vehicle safety devices can continue to work as intended. However, in this respect, it must be possible to detect with certainty whether a sensor has malfunctioned or is defective in order for the safety device to resort to the replacement values in that case. If false measuring values are not detected or a defect-free sensor is classified as being defective, the vehicle safety devices may operate in an erroneous or suboptimum manner.
Methods for detecting whether a malfunction or defect of a sensor has occurred are known and are already carried out within the sensor, i.e. the structural unit consisting of the measuring section and the sensor controller, which together form the integrated sensor, and output a logical value indicating whether or not the sensor is operating without malfunctions.
FIG. 1 schematically illustrates a known vehicle safety device 110 having a self-testing sensor 112 and a control unit 114. In order for the sensor to perform a self-test, a sensor controller (not shown) which is part of the sensor 112 activates the measuring section (not shown) of the sensor 112 in a first step I and thereby generates a test measuring value in response to the simulated activation. This test measuring value is then evaluated by the sensor controller in step II which finally generates the logical value or error marker in step III, indicating whether or not the sensor 112 is operating without malfunctions. The error marker is then transmitted from the sensor 112 to the control unit 114 of the vehicle safety device 110 (step IV). This type of self-test can be performed continuously.
However, the malfunction detection of these self-testing sensors is not precise enough in some conditions.
It is therefore the object of the present invention to improve the accuracy of a method for recognising a malfunction or defect of a self-testing sensor of a vehicle safety device.